Research Article
Intermittency Study of Charged Particles Generated in Pb-Pb
Collisions at
ffiffiffiffiffiffiffi
s
NN
p
=2:76 TeV Using EPOS3
Ramni Gupta and Salman Khurshid Malik
Department of Physics, University of Jammu, Jammu, Jammu and Kashmir, India
Correspondence should be addressed to Salman Khurshid Malik; maroozmalik@gmail.com
Received 29 November 2019; Revised 14 February 2020; Accepted 17 March 2020; Published 8 April 2020
Academic Editor:
Edward Sarkisyan-Grinbaum
Copyright © 2020 Ramni Gupta and Salman Khurshid Malik. This is an open access article distributed under the Creative
Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the
original work is properly cited. The publication of this article was funded by SCOAP
3
.
Charged particle multiplicity fluctuations in Pb-Pb collisions are studied for the central events generated using EPOS3 (hydro and
hydro+cascade) at
ffiffiffiffiffiffiffiffi
s
NN
p
=2:76 TeV. Intermittency analysis is performed in the midrapidity region in two-dimensional (η, ϕ) phase
space within the narrow transverse momentum (p
T
) bins in the low p
T
region (p
T
≤ 1:0 GeV/c). Power-law scaling of the
normalized factorial moments with the number of bins is not observed to be significant in any of the p
T
bins. Scaling exponent
ν, deduced for a few p
T
bins, is greater than that of the value 1.304, predicted for the second-order phase transition by the
Ginzburg-Landau theory. The link in the notions of fractality is also studied. Generalized fractal dimensions, D
q
, are observed to
decrease with the order of the moment q suggesting the multifractal nature of the particle generation in EPOS3.
1. Introduction
The strongly interacting dense state of matter, believed to
represent QGP (quark-gluon plasma) after its creation in
heavy-ion collision, rapidly cools into a spray of particles.
This array of particles carry signals of QGP and its properties
which can be directly and indirectly measured by detectors
that are encircling the collision point. Of the myriad of anal-
ysis tools to understand the dynamics of this particle produc-
tion [1] and phase changes in the matter while passing into
the QGP phase from the hadronic phase and vice versa, an
important one is the fluctuations study of the observables.
Lattice QCD predicts large fluctuations being associated with
the system undergoing phase transition. Multiplicity distri-
butions characterize the system formed or any phase transi-
tion in the heavy-ion collisions. Studies of multiplicity
fluctuations have prompted considerable advances in this
area of research. Large particle density fluctuations in the
JACEE event [2] and its explanation by normalized factorial
moments triggered investigations of multiplic ity fluctuation
patterns in multihadronic events with decreasing domains
of phase space [3]. The presence of power-law behaviour or
scale invariance of normalized factorial moments with
decreasing phase space interval or increasing bins is termed
as intermitte ncy [4, 5]. Observation of intermittency signals
the presence of self-similar and fractal nature of the particle
production. If fluctuations have a dynamical origin, the
underlying probability density will be reflected as intermit-
tency behaviour. The existence of dynamical fluctuations
can thus be studied using normalized factorial moments
(NFMs) [4] in one-, two-, or three-dimensional phase space.
The idea of intermittency has been obtained from the
theory of turbulent flow. There, it signifies as a property of
turbulent fluid: vortices of fluid with different size alternate
in such a way that they form self-similar structures. These
vortices do not necessarily fill in the entire volume, but they
instead create an intermittent pattern in the regions of lam-
inar fl ow. This property is given by a power-law variation of
the vortex-distribution moments on their size. So, the self-
similar nature of vortices directly creates a relation between
intermittency and fractality. Self-similar objects of noninte-
gral dimensions are called fractals [6]. A fractal dimension
is a generalization of an ordinary topological dimensionality
to nonintegers.
Hindawi
Advances in High Energy Physics
Volume 2020, Article ID 5073042, 8 pages
https://doi.org/10.1155/2020/5073042